I have a .270 T/C Encore that I had the 15 " barrel reduced to a 12" barrel and a muzzle break. All the .270 charts I see concerning velocities and energy are for rifles. Anyone have an idea of how much velocity and energy I loose with a 12" barrel and would a faster 130 grain bullet be better than a heavier 150 grain bullet for whitetail? Would the faster bullets like the Light Magnums be a better choice for the shorter barrel since I loose speed and energy? Do most handgun hunters use earplugs, the noise is unbearable and would seem to cause hearing damage. Do most invest in those gamewalker hearing protection and do they really work?

I would strongly suggest the use of hearing protection without the muzzle break or shortened barrel, certainly it is mandatory with a muzzle break. You risk permanent, and possibly severe, hearing damage by shooting such a pistol without protection. I can't speak for the gamewalker protection, but electronic earmuffs do work quite well. When I shoot a rifle or SSP with a muzzle break, I use ear plugs and ear muffs at the range, always.

I shoot a .284 Winchester in a 15" XP100, it's roughly the same case capacity as your .270 with the obvious slightly larger bore size. It will push a 120gr bullet to 2900+ fps. As a guess, I would say your 130gr loads would likely be in the neighborhood of 26-2700fps. If you want to see what gives you the best velocity, a chronograph is the only way to know for sure. I would stick with the 130gr bullet, it should be wholly adequate for deer sized game. What shoots best might also be a consideration, no matter the bullet weight, so long as it is an appropriate design for hunting. The light magnums might give you extra velocity, but you'll never know until you shoot them over a chronograph. I'll bet good odds the fireball alone will be worth the price of admission with those rounds.